[1121] Inflammatory Myofibroblastic Tumor of the Head and Neck (IMT-HN): A Light Microscopic, Immunohistochemical (IHC) and Cytogenetic Study of 6 Cases

AB Colanta, JL Hunt, R Tubbs, TM Elsheikh, KW Berean, BM Wenig. Beth Israel Medical Center and St. Luke's-Roosevelt Hospital Center, New York; The Cleveland Clinic, Ohio; Ball Memorial Hospital, Indiana; University of British Columbia, Vancouver, Canada

Background: IMT uncommonly occurs in the HN. IMT is believed to be a true neoplasm due to the detection of clonal cytogenetic aberrations involving the anaplastic lymphoma kinase (ALK) gene located on 2p23. The rearrangement and translocation of the ALK gene to form several fusion partners with, among others, tropomyosin 3 (1q22-23) and tropomyosin 4 (19p13.1) appear to be important in the oncogenesis of IMTs.
Design: 6 cases of IMT-HN were found from our collective files. The clinical and pathologic features were reviewed. IHC was performed on formalin fixed, paraffin sections using standard avidin-biotin complex method with microwave antigen retrieval for ALK-1, vimentin, desmin, actins smooth muscle and muscle specific, cytokeratins (AE1/AE3, CAM5.2, CK907), p63, S-100, HMB-45, myoglobin and CD68. Fluorescence in situ hybridization (FISH) was performed in 3 cases with available material on formalin fixed, paraffin sections using dual color, directly labeled, break apart format probes flanking the centromeric and telomeric regions of the ALK 2p23 locus (Abbott Molecular; Des Plaines, IL).
Results: All patients were males ranging in age from 15-64 years old (median, 40.5 years). Sites of occurrence include the larynx (5) and sinonasal tract (1). Histologic findings included a submucosal cellular proliferation with storiform to fascicular growth. The cells were spindled-shaped, stellate and/or epithelioid with enlarged round nuclei, eosinophilic nucleoli and abundant basophilic fibrillary appearing cytoplasm. Distinct eosinophilic intranuclear inclusions were seen in 4 cases. Scattered mitoses were identified; necrosis was absent. A mixed chronic inflammatory cell infiltrate was present. Lesional cells were immunoreactive for ALK-1 (3/6), vimentin (5/5), actins (3/4), desmin (1/4); all of the other markers were negative. ALK gene translocation was present in 3/3 cases.
Conclusions: IMT-HN may be diagnostically challenging, especially in its differentiation from other lesions, including spindle cell squamous carcinoma. The presence of ALK-1 immunoreactivity and/or gene rearrangements greatly assists in the diagnosis. However, detection of the ALK protein by IHC varies from 36-60% and the presence of atypical translocations may result in an absence of detection by FISH.
Category: Head & Neck

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 169, Monday Morning